Induction ofIRT1by the nickel-induced iron-deficient response in Arabidopsis

Abstract

Excessive amounts of nickel (Ni) can be toxic for plants. Recently, we reported that IRT1, the primary iron (Fe) uptake transporter in roots, meditates excess Ni accumulation in Arabidopsis thaliana. We also found that Ni exposure increases IRT1 expression in roots, suggesting that Ni uptake is further induced by Ni stress. Here, we show that Ni exposure induces expression of not only IRT1, but also FRO2, a ferric reductase in the root epidermis, and FIT, a transcription factor regulating the expression of genes involved in Fe homeostasis including IRT1 and FRO2. This result suggests that Ni accumulation induces an Fe-deficient response and leads to the induction of IRT1. Our findings suggest that excess Ni causes Fe deficiency at the molecular level and induces Fe deficiency signaling in plant cells.

Legume seeds and cereal grains’ capacity to accumulate iron while sprouting in order to obtain food fortifi cant.

“…A high concentration of this heavy metal in the growth medium or soil causes oxidative damage to cellular components (mainly lipids, proteins and nucleic acids) (Dietz et al, 1999) and may lead to the displacement of the correct metal ions in proteins' active sides (Nishida et al, 2012). The defense against excess of heavy metal ions, including iron, may be achieved by the avoidance strategy (extracellular precipitation, biosorption to cell walls, reduced uptake or increased effl ux).…”

“…The defense against excess of heavy metal ions, including iron, may be achieved by the avoidance strategy (extracellular precipitation, biosorption to cell walls, reduced uptake or increased effl ux). The other strategy -tolerance -allows a plant to survive a high iron concentration by intracellular chelation by amino acids, glutathione and ligands such as metallothioneins, phytochelatins, ferritin or compartmentation within vacuoles (Assunção et al, 2003;Clemens 2006;Cobbett 2000;Hall, 2002;Nishida et al, 2012;Yadav 2010;Yang et al 2005).…”

Optimal copper supply is required for normal plant iron deficiency responses

“…Consequences of metal toxicity are oxidative damage to cellular components, 5 or displacement of the correct metal from active sites in proteins. 6 Certain soils may have too little or low availability of metal micronutrients naturally, whereas other soils may have excess metals naturally or due to human activities. 7,8 Excess or deficient supply of one metal may lead to deficiencies or toxicities of other metals, thus there is a need for the plant to have crosstalk mechanisms to coordinate uptake, chelation, transport, or other gene expression mechanisms to maintain metal homeostasis.…”

Effects of foliar nickel (Ni) application on mineral nutrition status, urease activity and physiological quality of soybean seeds

“…This happens because tropical soils have iron availability for plants (Kämpf et al, 2012). In plants grown in nutrient solution Rahman et al (2005) found lower absorption of iron, which causes the two cations to compete with each other for absorption sites (Nishida, 2012). These authors found that the accumulation of Ni induces the expression of IRT1, an iron 1 transport regulator gene and member of the ZIP family, causing more Ni to be absorbed by that carrier.…”